Chapter 2

Determination of a Child's Sex

• The father's sperm determines the sex of a child, as it carries either an X or Y chromosome.
• A child with an XX pairing on the 23rd chromosome is most likely to be female.

Mendel's Discovery

• Gregor Mendel discovered that when two competing traits are present, one trait will dominate and be expressed, while the other trait will be recessive and not expressed.

Traits and Inheritance

• A recessive trait is present in the organism but not expressed.

Fertilization and Chromosomes

• During fertilization, the sperm provides either an X or Y chromosome, while the ovum provides an X chromosome.

Conception of Females and Males

• The likelihood of conceiving females is slightly higher than males due to the presence of X chromosomes in both sperm and ovum.

Genetic Counseling

• The primary focus of genetic counseling is to assist individuals in making informed decisions about their reproductive health.

Prenatal Testing

• Amniocentesis involves examining a small sample of fetal cells drawn from the amniotic fluid.
• Karyotype involves examining the chromosomes of an individual to identify any genetic abnormalities.
• Chorionic villus sampling (CVS) differs from amniocentesis in that it involves examining a sample of placental cells instead of amniotic fluid.

Role of Genetic Counselors

• Genetic counselors use genetic data to assist individuals in making informed decisions about their reproductive health.

Teratogens and Fetal Development

• A teratogen is an agent that can cause harm to a developing fetus.
• A mother's diet can impact the development of the fetus, and certain nutrients are essential for fetal growth.
• Parental behavior can affect the child's development, and certain aspects of behavior can increase the risk of birth defects.
• Teratogen sensitivity varies during prenatal development, with certain stages being more vulnerable to harm.

Global Concerns and Pregnancy

• Approximately 50 million pregnancies worldwide end in abortion each year.
• The primary global concern related to diet is the lack of essential nutrients for fetal development.
• A key precaution for individuals planning to become pregnant is to ensure adequate nutrition and avoid harmful substances.

Pregnancy and Lifestyle

• Certain substances, such as drugs and alcohol, should be avoided during pregnancy to minimize harm to the fetus.
• Smoking is not recommended during pregnancy, as it can increase the risk of birth defects.
• A healthy environment should be optimized for pregnancy, including a balanced diet and minimal exposure to harmful substances.
• Folic acid intake should be monitored to ensure adequate levels for fetal development.

Test your knowledge on threats to the fetal environment and how to mitigate them. Learn about the impact of parental behavior and teratogens on child development. This quiz is based on content from The Prenatal Environment: Threats to Development.